Environmental concerns have led to an attempted reduction of pollutants from a multitude of sources. Manufacturing facilities, have been required to operate under increasingly stringent emissions guidelines. These emissions guidelines require, in part, a reduction of volatile organic compound (VOC) emissions.
In a manufacturing environment, VOC's have a wide variety of uses. For example, certain VOC's have been commonly employed for the purpose of cleaning and preparing various plastic components for receiving a material coating, such as paint. More specifically, such VOC's are particularly useful for cleaning and preparing thermoplastic polyolefin (TPO) components for coating with a primer or paint product. Not only are such VOC's effective for the removal of grease and other contaminants which may reside on these components, they also act on the surface of the TPO to promote adhesion with the forthcoming primer or paint coating.
In an attempt to reduce emissions, it has become essential to drastically reduce or eliminate the use of VOC's. For similar reasons, most automobile manufacturers also now employ a water-based paint and/or primer rather than traditional solvent-based products.
New plastic formulations have been developed which may be cleaned via non-VOC methods, and which are better able to bond with water-based paint and/or primer. However, TPO exhibits inherently poor wettability—meaning that it tends to repel moisture. Without the use of trichloroethylene or similar materials to prepare the surface, providing adequate paint adhesion is of great concern. For this reason, manufacturers utilizing a water-based cleaning system and water-based paint, typically provide the TPO components with a primer coat prior to the final paint or color coat.
Unfortunately, primer coating is a costly process. One reason is that a large portion of the sprayed primer is typically lost rather than deposited on the component. Additionally, once the components have received a primer coat, it is generally necessary to cycle them through an oven to allow the primer to fully dry. Therefore, it is desirous to develop a system and method that will allow a paint coating to be applied directly to the surface of a TPO component, without the need to first apply a coat of primer.
The present invention satisfies this need. The system and method of the present invention applies a water-based adhesion promoter to each TPO component. The adhesion promoter application preferably occurs after the component has undergone a cleaning process. After the adhesion promoter is applied and dried, a thin layer will remain on the surface of the TPO component. This thin layer of adhesion promoter is sufficient to provide the necessary adhesion between the component and the forthcoming paint coat.
The adhesion promoter application system of the present invention may monitor a variety of parameters during operation, including, for example: line speed of the component; temperature of the component; temperature of the adhesion promoter; adhesion promoter nozzle distance and angle; adhesion promoter flow rate; nozzle spray pattern; setting zone time, temperature and relative humidity; and pre-oven and oven time, temperature and relative humidity. The adhesion promoter application system of the present invention may also be adapted to distinguish when a part is present within the system and to provide periodic water flushing in order to prevent adhesion promoter build-up.
Therefore, the adhesion promoter application system of the present invention allows a paint coat to be applied to the surface of a TPO component without the need to first apply a primer coat. As such, the present invention may provide a reduction in material, equipment and labor costs, as well as an increase in production capacity.